Rotary bonded abrasive articles



Oct. 1, 1935. A, E

ROTARY- BONDED ABRASIVE' ARTICLES Filed Dec. 1, 1933 INVENTOR.

ARTHUR H. PREY It'll!!! l lllll llll|l...lll\lllllllllllllllllnlATTORNEY.

Patented Oct. 1, 1935 I PATENT OFFICE ROTARY BONDED annasrvr: narrowsArthur H. Prey, Niagara Falls, N. Y., assignor to The CarborundumCompany, Niagara Falls, N. Y., a corporation of Pennsylvania ApplicationDecember 1,1933, Serial No. 700,409 In Canada September 26, 193g '1Claims. (01. 51-206) This invention relates to the manufacture ofabrasive articles and particularly to thoseabrasive articles comprisinga bonded abrasive shape mounted on a rotative spindle.

The object of the invention is to provide an improved article forabrasive purposes and a method of making the same.

This application is a continuation-in-part of my copending applicationSerial No. 569,723, filed October 19, 1931.

Certain arts and professions require bonded abrasive articles of suchsmall sizes that they can be operated satisfactorily only when they havebeen mounted on m'etallicspindles adapted to fit into suitable chucks.mounted abrasive articles in grinding teeth, preparatory to suchsubsequent operations as filling or capping to prevent further decay ofthe teeth. Die and tool makers also find such mounted abrasive articlessuitable for removing metal from small corners or crevices.

Inasmuch as experience has taught that the abrasive portion of sucharticles is best adapted to the purpose when made by abaking or kilnfiring process, it has become customary to manufacture these abrasiveportions and then, after they have been hardened by the heat, cementmember to the spindle.

spindles are, as a general rule made of a type .T of steel known asdrill rod steel and fabricated in aspecial manner to increase strengthin the nose. It is not feasible to mold the abrasive portion onto themetallic spindle and then set the abrasive binder, because the bakingtemperatures of such binders is in a temperature range that is decidedlydeleterious to the metals which, as above mentioned, are commerciallyavilable for this purpose.

The usual practice heretofore has been to provide the abrasive memberwith a hole of suitable size to receive a steel spindle and suitablequantity of cement for joining the abrasive member to the shaft. Italsohas been the practice to use a cold setting cement, such as afreshly'made mixture of calcined cupric oxide and phosphoric acid, forthe purpose of joining the abrasive This prior practice, however, hasleft much to be desired because of the abrasive member becoming detachedfrom its spindle before it has done its .full measure of grinding.Numerous cements have been tried for the purpose but it is the practiceto use a cement of the oxyphosphate type such as ,a mixture of calcinedcupric acid oxide andphosphoric acid, although some- Dentists use thesetimes even this type of cement has'failed to hold the abrasive memberonto the shaft the desired length of time.

I at first thought that the diiiiculty was due to r the smoothness ofthe surface of the metal shaft scertain metals and then using the abovementioned cement to attach the abrasive member. a remarkably tenaciousbond is effected which will last until the last of the abrasive grain isworn off.

While a considerable number of theories have been suggested and examinedto explain the phenomena underlying the improved results I obtain, theexplanations so far advanced are not entirely satisfactory in explainingthe mechanism whereby the results are obtained. However, I have observedcertain indications of deterioration of the cement when applied directlyto the steel shaft or to a nickel plated shaft, which. I offer for whatthey are worth. For instance, I have noted that the cement immediatelysurrounding the steel shaft often is, porous as though tiny bubbles hadbeen present when the cement was soft.

My invention will be better understood after a brief description of suchan abrasive device; and for purposes of illustration I have shown atypical abrasive device of this type in the attached drawing in which:

Figure 1 is an enlarged-cross-sectional view through the longitudinalaxis of the spindle; and 35 Figure 2 is an enlarged cross-sectional viewthrough the plane-IIII of Figure 1.

In the drawing, the abrasive member I is shown as attached to thespindle 2 by means of a suitable cement 3. The spindle 2 is shown with acoating 40 4 of a material that improves the bond over that obtained bycementing the member directly to the spindle 2.

Among the materials that I have found satisfactory for carrying out myinvention are copper,

chromium, cadmium, silver, gold, or other such material, and a dualplating of first copper and thennickel over the copper. Because copperis readily available at low cost and is easily applied and efficacious,I will describe my invention by referring specifically to the use ofcopper.

According to my invention the whole spindle, or the end of the spindleto be attached to the abrasive member and which may or may not beknurled as desired, is first cleaned with a caustic Rassuao sodasolution'to remove grease and oil and then, upon scouring with clean,moistened pumice, washed with a dilute solution of hydrochloric acid.

When the spindle is free from grease, oil and other surface impurities,I coat it with copper. The copper coating may be applied by dipping theclean spindle in a solution or copper sulphate and sulphuric. acid, butI prefer to coat the spindle by electr p t When the spindle, or thatportion of the spindle that is to come into contact with the cement, isthoroughly coated with copper, it is washed and dried and is 'ready foruse.

In joining the abrasive member (which, for the purpose of niy inventionmay be of vitrified-bonded granules resin-bonded granules or any othersuitably bonded material) to the copper-coated shaft, I use a cementcontaining calcined cupric oxide and phosphoric acid in the ratio ofapproximately 30 grams of cupric oxide to '7 cubic centimeters of anaqueous solution containing 80% phosphoricjacid. I quickly mix thesematerials to form a paste and then apply a small portion to thecopper-coated end of the spindle, and thenment sets quickly and requiresrapid manipulation from the time the copper and phosphoric acid aremixed until the bonded abrasive member is correctly-positioned on thespindle. When the cement has-set, the bonded abrasive member and thespindle are so firmly joined that the abrasive member may be used insevere service without danger of its becoming loose from the spindle.

Whilaas stated above, copper was given as the specific material forillustrative purposes, other materials also are efiicacious. Among theother used without'departing from my invention. One

method of metal coating that has found wide use in the arts is carriedout by means of an imple- '{ment known as the Schoop gun. This devicemolten metal away from the flame and onto any object to which the gun isdirected. By this means a tightly adhering coating of metal may beapplied to a spindle or any desired portion of a spindle.

Having thus described my invention, I claim: 5

1. An abrasive article comprising a bonded abrasive article joined to ametallic spindle by a cement of the oxyphosphate type, said metallicspindle being coated with a film of a metal of the group consisting ofcopper, cadmium, nickel, silver, gold and chromium where it comes incontact with the cement.

2. An abrasive article comprising a bonded abrasive article joined to ametallic spindle by a cement of the oxyphosphate type, said metallicspindle being knurled and being coated with'a film of a metal of thegroup consisting of copper, cadmium, nickel, silver, gold and chromiumwhere it comes in contact with the cement.

3. An abrasive article comprising a bonded abrasive article joined to ametallic spindle by a cement consisting of a mixture of cupric oxide andphosphoric acid, said metallic spindle being coated with a. film of ametal of the group consistizm of copper, cadmium, nickel, silver, goldand chromium where it comes in contact with the cement.

4. An abrasive article comprising a bonded abrasive article joined .to ametallic spindle by a cement consisting of a mixture of cupric oxide andphosphoric acid, said metallic spindle being knurled where it comes incontact with the cement and being coated with a film of a metal of thegroup consisting of copper, cadmium, nickel, silver, gold and chromiumwhere it comes in contact with the cement.

5. An abrasive article comprising a bonded abrasive article joined to ametallic spindle by a cement of the oxyphosphate type, said metallicspindle being coated with a film of copper where 40 it comes in contactwith the cement.

' 6. An abrasive article" comprising a bonded abrasive article joined toa metallic spindle by a cement of the oxyphosphate type, said metallicspindle being coated with a film of cadmium where it comes in contactwith the cement.

"'7. An abrasive article comprising a bonded abrasive article joined toa metallic spindle by a cement of the oxyphosphate type, said metallicspindle being coated with a film of silver where it comes in contactwith the cement.

AR ii-I i" H. PREY.

